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September 2010

September 09, 2010

On my last visit to India, I walked into a restroom at the airport in Bangalore, the high-tech capital of India, and was greeted by an attendant whose job was to dispense liquid soap and paper towels. The work was, of course, superfluous, but he clearly needed the job and the tips he occasionally received. Perhaps his labor could have been put to a more productive use elsewhere.

But anyone who has seen the vast ocean of humanity in a large developing country like India has to wonder what kind of productivity can truly provide a decent life to everyone. India’s high-tech mecca is full of people with low-tech skills or no skills at all, who provide their labor in myriad ways to keep the city running while elite engineers write software and design computer chips. Labor is not a scarce commodity in many developing regions of the world.

In contrast, labor productivity is central to any discussion of the U.S. economy. High labor productivity has been cited as one of the reasons for the slow job growth in the current economic recovery. Still, many economists believe that productivity growth, which allows goods and services to be produced at decreasing cost, is the ultimate source of wealth for everyone. In competitive markets, lower production costs mean lower consumer prices, which stimulate demand and lead to further increases in productivity and, ultimately, wages. But this conventional argument ignores the crucial role of natural resources in production and consumption.

Labor remains expensive relative to natural resources such as energy and raw materials in industrialized countries. In response, new technologies are designed to reduce and eliminate human labor, making the remaining workers more and more productive. In the past 100 years, the farm sector has gone from using 40% of the U.S. workforce to just 2%. The manufacturing sector continues to lose jobs to automation and the use of cheaper labor overseas. We now transact much of our routine business with the likes of banks, bookstores, and airlines without ever seeing a human face or hearing a live voice.

Is it possible that we are over-optimizing one factor of production -- labor -- at the expense of other resources that are truly scarce? One way to answer this is to look at the biologically productive land and water area required to support our resource consumption and waste output.

Redefining Progress, a nonprofit organization that develops tools and policies for sustainability, estimates that it takes 9.57 hectares to support an average American. This ecological footprint is about 80% higher than locally available regenerative and absorptive capacity. The deficit is made up through imports and disproportionate use of global resources such as the atmosphere. The per-capita footprint is 1.36 hectares in China (36% above capacity) and 0.76 hectares in India (9% above capacity). Humanity’s total ecological footprint is nearly 16% higher than earth’s capacity, indicating an unsustainable depletion of natural capital.

The United States has the largest per-capita ecological footprint among all nations and consumes more than 20% of the world’s resources. Developing countries aspire to a similar living standard but face the enormous task of lifting hundreds of millions out of deep poverty. Their plan for economic growth depends on using large amounts of additional natural resources. China, for example, has become an insatiable consumer of energy and raw materials, with its energy consumption expected to more than double by 2030.

At the time of such unprecedented resource use, nearly 750 million people around the world are either unemployed or classified as “working poor”, according to the International Labor Organization. More than 500 million additional workers will enter the world’s labor markets by 2015.

A number of resource economists and sustainability thinkers have advocated an environmental tax shift in developed nations, which would reduce the tax burden on labor and increase it on fossil fuels, virgin raw materials, waste generation, and pollution. The idea is to encourage more employment of labor and less of scarce natural resources. Tax shifting is finding much more traction in Europe than in the United States.

In developing nations where labor costs are low and raw materials are relatively expensive, resource-saving and employment-generating activities such as repair and remanufacturing are already widespread. But technologies and lifestyles borrowed from rich countries -- including private automobiles and disposable products -- could destroy any possibility of sustainable development in these countries. What they lack -- and perhaps need the most -- are policies and technologies designed to radically increase resource productivity and employment opportunities in tandem.

It is difficult to imagine a livable future where unemployment and underemployment are rampant and the use of natural resources remains unrestrained. Both developed and developing nations face the same ultimate challenge: moving from a narrow view of productivity to a balanced consideration of how best to employ both human and natural resources.

September 07, 2010

It is now standard practice to use the IPCC (2006) guidelines for modeling soil GHG emissions in life-cycle assessments of agricultural products. While this generally works well enough, it is possible sometimes to have a disconnect between a specific empirical model and the corresponding physical reality. One such instance is the modeling of nitrous oxide (N2O) emissions from legumes. [Caution: This is a long, technical note.]

Legumes include forage crops (such as alfalfa and clover), grass-legume mixes, and annual food crops (such as soybeans, beans, chickpeas, peas, and lentils). Legumes differ from other crops in that they require little or no nitrogen fertilizer. The symbiotic nitrogen-fixing bacteria in the root nodules supply these plants with fixed nitrogen in the form of ammonium and in return the plant provides the bacteria with carbohydrates and other organic compounds to fuel the energy-intensive process. Under the right conditions – such as when excess ammonium is produced, or when uptake of nutrients and water by the plant is reduced in the late growth or ripening stage – the root nodules can secrete the excess ammonium into the soil. In theory, some of this can escape into the atmosphere as N2O via nitrification and denitrification.

While N2O emissions from leguminous plants have been studied for decades, the processes are still not well understood. Two recent studies of soybeans shed some light on the time profile of N2O emissions over the life cycle of the plant. A field study conducted in Argentina (where soybean is one of the most important crops) by Ciampitti, et al (2008)showed that N2O emissions were low and stable during 100 days after sowing and increased after the grain-filling stage. Harvest occurs somewhere around 120 days after sowing, and the crop life cycle amounts to just one-third of a full year. The highest N2O emissions occurred from about 20 days before harvest till about 20 days after harvest. Yang and Cai (2005)also found that 94% of the total N2O emissions were concentrated in the last stages of the soybean crop life cycle as shown below.When the roots ceased growing in the ripening stage, soil nitrogen and water uptake decreased and the available nitrogen was released into the soil from the senescence (as expected) and then the decaying of the roots and nodules.

A conservative estimate based on Yang and Cai (lower than estimates based on Ciampitti) would suggest emissions of about 0.6 Kg N2O-N/acre (or 1.5 Kg N2O-N/ha) considering just the late growth stage immediately prior to harvest. This can be a significant source of GHG emissions in soybean production. It gets more complicated when synthetic nitrogen fertilization and bacterial inoculation are added, but the trend remains the same: N2O emissions are concentrated and high in the last stages of the cycle.

Rochette and Janzen (2005)provide a lengthy summary of legume N2O emissions from a literature survey spanning nearly 25 years. Their average N2O emissions for all annual crops are 1 Kg N2O-N/ha, lower than my low estimate of 1.5 from Yang and Cai for soybeans. They argue that their average figure is only slightly greater than background emissions from agricultural crops. There are some consistency problems with this:

The average emissions are based on a wide range of disparate studies. One of the key variables – the length of the experiment (measurements) counted in days – varies significantly between studies. Some of them may not have captured the critical emission phases of crop life cycles.

The background emissions cited (@ 0.4 to 1 Kg N2O-N/ha) are for a full year, and not specifically related to the locations of the legume studies.

Averaging a large number of results from the literature without any adjustments is not the best way to quantify these N2O emissions. This paper does show, however, that the previous IPCC (1996) methodology overestimated N2O emissions from biological nitrogen fixation (3.2 to 5 Kg N2O-N/ha).

In another recent study, Zhong et al (2009)concluded that biological nitrogen fixation was not a direct source of legume N2O emissions. But their comparison of lentil, pea and soybean goes only till 45 days after planting, which does not come close to the timing of the peak N2O emissions for soybeans. Lentils reach maturity about 100 days after emergence, but the Zhong study seems to stop measurements less than 100 days after planting, increasing the likelihood of missing any late stage emissions in the lentil life cycle.

I have attempted to show here that studies of legume N2O emissions have been rather inconsistent and at least some legumes are likely to have significant N2O emissions from nitrogen fixation (soybeans surely do). There is a great deal of uncertainty in quantifying these emissions, but it should be clear that they cannot be ignored.

Based on a recommendation by Rochette and Janzen, IPCC (2006) does not include biological nitrogen fixation as a direct source of N2O, instead relying solely on the nitrogen inputs from crop residues (above and below ground) to account for all legume N2O emissions. The problem with this is that the IPCC crop residue model does not seem to capture the magnitude of N2O emissions in the late-growth stages of soybeans (this is the one crop that I have looked at in detail; others may have a similar problem). There is in fact almost an order of magnitude difference between the worst-case (high) N2O emissions from crop residue and the conservative (low) N2O emissions in the late-growth stages (crop residue emissions are smaller by a factor of 5 to 10).

I am not necessarily suggesting that IPCC’s approach is wrong. It can be made to work. But, at a minimum, it does look like the empirical model parameters have not been calibrated to correctly capture the soybean emission profile. We will attempt to contact the appropriate IPCC authors and begin a conversation on the need for reviewing this whole issue. In the meantime, our internal modeling will continue to compensate for this discrepancy.